An air battery is a battery (cell) that uses oxygen in the air as a cathode active material and a metal such as aluminum (Al), iron (Fe) and zinc (Zn) as an anode active material.
Since oxygen in the air is used as a cathode active material, it is not required for such batteries to store a cathode active material in the battery case. This enables high energy density, small size and light weight of a battery, and applications as a power supply of portable devices and also as a drive power supply for electric vehicles and the like has been expected.
To put such air batteries into practice, for example as a drive power supply for cars, it is required to serially connect a plurality of large batteries in series in order to achieve a required high output voltage and a required large capacity.
For example, Japanese Patent No. H07-085899 describes a technique for stabilizing the electrical contact between terminals of adjacent cells so as to reduce fluctuation in output voltage. The technique involves a first terminal that is electrically connected to a first electrode of a cell and a second terminal that is electrically connected to a second electrode of the cell and is in contact with a first terminal of the adjacent cell, in which one of the first and second terminals is formed in a shape with a flat surface while the other is formed in a shape of elastic separate plates that elastically come in contact with the flat surface.
In the current collecting structure described in Japanese Patent No. H07-085899, the electrical connection from an aluminum electrode (anode) to the next air electrode (cathode) is achieved via a current collecting wire, an anode current collecting frame, the second terminal and the first terminal. The two terminals are connected to each other by abutment using a spring.
That is, the electrical connection between cells is achieved through a path that runs out of the cells in both of the cathode and anode. Accordingly, a problem is that the long current collecting path results in very large current collecting loss. This problem is more significant and more serious in larger and higher-power batteries.